Monday, November 09, 2009

First in the Nation

This past July, Missouri debuted the first Diverging Diamond Interchange in the U.S. at Interstate 44 and MO 13 in Springfield. 

In brief, the Diverging Diamond temporarily shifts traffic into the opposite lanes so that left turns have no opposing traffic to cross. In this instance, the Northbound lanes of MO 13 cross into the Southbound lanes while the Southbound lanes cross into the Northbound lanes. This diagram should help explain:


The lanes themselves are separated by a Jersey Barrier and the crosspoints are signalized.


Simple enough, right? Well, not quite. MoDOT reports that once people become accustomed to this type of interchange, it works fine. However, the local TV stations reported at least one motorist going the wrong direction within a hour of the interchange opening to traffic. Fortunately, there was no report of a collision with other motorists.

Overall, MoDOT seems happy with the Diverging Diamond and has begun work on another at James River Freeway (US 60) and National Ave in Springfield. This one, however, will entail building extra lanes along US 60 between National and Campbell (US 160) and construction of an underpass to improve connection to the nearby Cox Hospital and provide easier access between CoxHealth facilities located on both sides of National Ave just north of US 60. 

Eventually, more Diverging Diamonds will be constructed, including along I-435 in Kansas City and US 65 in Springfield.


1 comment:

Anonymous said...

I have been familiar with the Mo-13 and I-44 interchange and remember the backups last year (2008). I came to Springfield in November this year expecting the same thing and to my surprise, this was the solution. It is a fine "temporary" fix, but a new interchange is still needed as this is the main route from Kansas City to Springfield.

Pete